Veldhuyzen Willem F, Pande Praveen, Rokita Steven E
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
J Am Chem Soc. 2003 Nov 19;125(46):14005-13. doi: 10.1021/ja036943o.
A 9-aminoacridine conjugate of a silyl-protected bis(acetoxymethyl)phenol (bisQMP) was synthesized and evaluated as an inducible cross-linking agent of DNA to test our ability to harness the chemistry of reactive quinone methide intermediates (QM). The acridine component was chosen for its ability to delivery an appendage to the major groove of DNA, and the silyl-protected component was chosen for its ability to generate two quinone methide equivalents in tandem upon addition of fluoride. This design created competition between reaction of (1) the 2-amino group of guanine that reacts irreversibly to form a stable QM adduct and (2) the more nucleophilic N7 group of guanine that reacts more efficiently but reversibly to form a labile QM adduct. This lability was apparently compensated by co-localization of the N7 group and QM in the major groove since the N7 adduct appeared to dominate the profile of products formed by duplex DNA. The controlling influence of acridine was also expressed in the sensitivity of the conjugate to ionic strength. High salt concentration inhibited covalent reaction just as it inhibits intercalation of the cationic acridine. As expected for QM formation, the presence of fluoride was indeed necessary for initiating reaction, and no direct benzylic substitution was observed. The conjugate also cross-linked DNA with high efficiency, forming one cross-link for every four alkylation events. Both alkylation and cross-linking products formed by duplex DNA were labile to hot piperidine treatment which led to approximately 40% strand scission and approximately 50% reversion to a material with an electrophoretic mobility equivalent to the parent DNA. All guanines exhibited at least some reactivity including those which were recalcitrant to cross-linking by an oligonucleotide-bisQMP conjugate designed for triplex formation [Zhou, G.; Pande, P.; Johnson, A. E.; Rokita, S. E. Bioorg. Med. Chem. 2001, 9, 2347-2354].
合成了一种硅烷基保护的双（乙酰氧基甲基）苯酚（双QMP）的9-氨基吖啶共轭物，并将其作为DNA的诱导交联剂进行评估，以测试我们利用反应性醌甲基化物中间体（QM）化学性质的能力。选择吖啶组分是因为它能够将一个附属物递送到DNA的大沟中，选择硅烷基保护的组分是因为它在加入氟化物后能够串联产生两个醌甲基化物当量。这种设计在以下两种反应之间产生了竞争：（1）鸟嘌呤的2-氨基不可逆地反应形成稳定的QM加合物；（2）鸟嘌呤的亲核性更强的N7基团更有效地但可逆地反应形成不稳定的QM加合物。由于N7加合物似乎主导了双链DNA形成的产物谱，这种不稳定性显然通过N7基团和QM在大沟中的共定位得到了补偿。吖啶的控制影响也表现在共轭物对离子强度的敏感性上。高盐浓度抑制共价反应，就像它抑制阳离子吖啶的嵌入一样。正如QM形成所预期的那样，氟化物的存在确实是引发反应所必需的，并且没有观察到直接的苄基取代。该共轭物还能高效地交联DNA，每四次烷基化事件形成一个交联。双链DNA形成的烷基化和交联产物对热哌啶处理不稳定，这导致约40%的链断裂和约50%的产物回复为电泳迁移率与亲本DNA相当的物质。所有鸟嘌呤至少都表现出一定的反应性，包括那些对用于形成三链体的寡核苷酸-双QMP共轭物交联具有抗性的鸟嘌呤[周，G.；潘德，P.；约翰逊，A.E.；罗基塔，S.E.生物有机化学与药物化学2001，9，2347 - 2354]。
